Both State and Federal governments have issued regulations governing hazardous organic and inorganic contaminants in the environment. Subsurface soil and groundwater contamination with organic and inorganic contaminants has been the concern of State and Federal government since the 1970's. Action levels and clean-up standards have been promulgated by both State and Federal government for numerous organic and inorganic contaminants. Regulated organic contaminants in the subsurface environment include, but are not limited to: polychlorinated biphenyls (PCBs); chlorinated volatile organic compounds (CVOCs) such as tetrachloroethene (PCE), trichloroethene (TCE), trichloroethane (TCA), dichloroethene (DCE), vinyl chloride; fuel constituents such as benzene, ethylbenzene, toluene, xylene, methyl tert butyl ether (MTBE), tertiary butyl alcohol (TBA), polynuclear aromatic hydrocarbons (PAHs), ethylene dibromide (EDB); pesticides such as (but not limited to) DDT; herbicides such as (but not limited to) silvex. Regulated inorganic contaminants in the subsurface environment include: heavy metals, such as lead, arsenic, chromium, mercury, and silver. The State and Federal regulations that govern these subsurface contaminants outline a protocol for subsurface investigation to identify the extent of contamination, identification of the human health and ecological risk posed by the contaminants, development of remedial action alternatives for reducing or eliminating any significant risk posed by the contaminants, and selection and implementation of remedial measures to achieve the remediation goals.
In situ (ISCO) and ex situ (ESCO) chemical oxidation technologies have emerged as prominent remedial measures due to cost-effectiveness and timeliness for achieving remediation goals. This technology can be used alone or in combination with other complementary technologies, such as soil vapor extraction (SVE) for removal of volatile organic compounds from the unsaturated zone, multi-phase extract for removal of organic contaminant from the unsaturated and saturated zones, or vertical recirculation systems in the saturated zone. ESCO can be applied by excavating subsurface soil and spraying or mixing chemical oxidants into the soil. ESCO can also be applied to solid surfaces such as vehicles and equipment.